Liquid distributors and collectors are used in column chromatography in order to uniformly distribute and to collect the liquid over the flow cross section. This is a necessary prerequisite to achieve the desired separating performance.
In order to accommodate the amounts of adsorbent required for the purification of the ever greater feed volumes in a column, development in chromatography is in the direction of larger column diameters, since there is an upper limit in the column length owing to the pressure drop and a minimum residence or process time. In order still to enable good separating performances in these columns with large cross-sectional area in relation to the packing height, new types of liquid distributors and collectors are required for equal distribution.
Known liquid distributors and collectors have slot construction (WO 03/005018 A1, WO 02/093159 A2, WO 98/55198), in which the input and output is via a central opening, and a narrow slot between opening and packing is intended to ensure uniform distribution. With increasing flow cross section, the uniformity of the distribution decreases as a result of the different lengths of the flow path (from the opening to the middle and from the opening to the edge of the packing cross section). A further approach consists in distributing the liquid toward the packing and collecting it by means of several openings (WO89/11901, WO99/48599). Equal distribution is ideally achieved by virtue of the same volume flow rate corresponding to each opening and the same residence time to each flow path. In construction terms, this is achieved by the same length and the same flow resistances (pressure drops) for the flow channels. With an increasing number of openings (>32), it is no longer possible to fulfill all criteria at the same time. This results either in solutions with complex flow channel geometries or, on the other hand, geometries which ensure equal distribution only for a certain volume flow rate.
A proven principle for the distribution of liquid between a relatively large number of openings with increasing flow cross section envisages the use of branching flow channels based on symmetrical T-distributors (U.S. Pat. No. 4,537,217, WO 99/48599). As a result of the equal length and geometric similarity of the flow channels, this principle ensures the same flow resistance and hence equal volume flow rates and equal residence times. However, with increasing flow cross section, it is not possible for all abovementioned criteria with regard to flow to be satisfied simultaneously for all cross-sectional shapes; equal length of the flow channels and equal flow resistances with large flow cross sections are achievable only with square flow cross sections (U.S. Pat. No. 4,537,217), while the same distribution of volume flow rates between the openings through strictly geometric distribution (WO 99/48599) can be obtained only by complex three-dimensional flow channel arrangements.
A design of the liquid distributors and collectors for chromatography columns which have a large diameter in relation to packing height is to date unknown with regard to the residence time of the liquid in the flow channels.
Proceeding from the prior art, it is thus an object of the invention to provide a liquid distributor and collector which can be designed even for large flow cross sections and, through uniform distribution, ensures the prerequisite for good separating performance, is subject to no restrictions with regard to its shape and can be manufactured in a very simple manner.